"I've seen an octopus brain or two in my time..."

Count me!
Maybe it’s just because I’m weird and I have a weird sense of humor, but I’m actually not having that much trouble understanding this novel. I think part of what helps is a certain attitude, which I will now share with you:
Nothing is going to make sense right away. Accept that. The first time you see a character or situation mentioned, you won’t know what it is, and it’s possible that you won’t for a long time. Pynchon will probably get around to clarifying some things. Not everything, but some things. Just read slowly and carefully, and accept the things you don’t understand with a grin, and keep going.
(Parenthetical aside to demonstrate personal brilliance, and insult to Ginger. Self-congratulatory laughter.)
The thing I really love about this book is that it reminds me why I write fiction in the first place. The novel form is liberating. You can do almost anything, and I think I can see why Pynchon will never let anyone adapt this novel to a play or a film. Those forms are restrictive, and many of the things that he achieves on the page couldn’t be done in another medium. This is the novel taken nearly to its limit (I think House of Leaves probably goes further than this does), and Pynchon as an artist is testing the capabilities of prose as he tells a story. It’s beautiful to watch. I would say it’s inspiring, but let’s not get sappy.
I didn’t think Gravity’s Rainbow would be as fun as it’s turned out to be. I hope it continues.